Chapter 2 Section 2 Notes

1. Chapter 2 Section 2 Notes Matter and Energy

2. Kinetic Theory of Matter: • Useful for seeing differences in the 3 common states of matter on earth: solid, liquid, and gas.

3. Kinetic Theory of Matter3 Main Points • All matter is made of atoms and molecules which act like tiny particles that are always in motion. • The higher the temperature, the faster the particles move. • At the same temperature, heavier particles move slower than lighter particles.

4. States of Matter • Solid: particles are in a fixed position • rigid structure; no freedom to change positions • Particles are held closely together by strong attractions • Diagram:

5. Liquid • Liquid: particles are closely packed, but can still slide past each other • Take the shape of their container • Particles are close but not as close as a solid • Particles can move randomly and spread on their own • Diagram:

6. Viscosity: • Viscosity: resistance of a fluid to flow • syrup is more viscous than water • Determined by the attraction of particles: the stronger the attraction, the more viscous (thick) the liquid is.

7. Gas • Gas: particles are in a constant state of motion and rarely stick together • expand to fill available spaces • Example: scents of food or perfume • Diagram:

9. Gas • A balloon filled with helium is under pressure: Pressure: force exerted per unit area of a substance • If there is too much pressure (too many helium particles) in a balloon, what happens? • A gas under pressure will escape the container if possible. Think about an air filled balloon that you let go.

10. Kinetic Theory • Using the Kinetic Theory of matter, explain why a balloon filled with helium goes flat faster than one filled with regular air.

11. Fluids • Fluids: substances that can spread • Both liquids and gases can spread, so they are considered fluids.

12. Plasma • Plasma: most common state of matter in universe: NOT on Earth • Makes up 99.9 % of the universe • Plasma is superheated gas and is a collection of free moving electrons and ions; the term came about in 1920’s to represent electrically charged particles at high energy

13. Plasma • Examples of plasma on earth • lightning • fire

14. Energy • Energy: the ability to change or move matter • Examples of energy or sources of energy: • heat, light, spring coiling, batteries • Energy must be ADDED to melt or evaporate substances • Aluminum must be melted before it can be recycled • As aluminum particles gain heat, particles move faster and break away from fixed positions and become liquids: called melting

15. Energy • Energy must be RELEASED to make a gas become a liquid or solid again. • When H2O is a gas and molecules slow down the water vapor returns to a liquid (called condensation). When molecules slow down even more, the water goes to a solid (ice).

16. Energy • Energy relationship between solid, liquid, and gas diagram: liquid gas solid Energy ABSORBED Energy RELEASED

18. Important Note: • Changing the state of matter does NOT change the substance or mass. • Water, steam, and ice are all H2O: the only change is the nature of attraction between molecules

19. Phase Change Diagram: Solid Melting Sublimation Deposition Freezing Condensation Liquid Gas Evaporation

20. Phase Changes • Evaporation: change of a substance from a liquid to a gas. • Condensation: change of a substance from a gas to a liquid. • Sublimation: change of a substance from a solid to a gas. • Deposition: change of a substance from a gas to a solid • Example: Water vapor without becoming liquid- this is how snow forms in clouds.

21. Law of Conservation of Mass • Law of Conservation of Mass: Mass cannot be created or destroyed • Example: Burning a match: consider what you start and end with.

22. Trivia Question • Trivia Question: If mass cannot be created or destroyed, then why do we have to replace our tires when the rubber “wears away”?

23. Law of Conservation of Energy • Law of Conservation of Energy: Energy cannot be created or destroyed • Energy can be converted from one form to another. • Example: A wristwatch: from chemical energy to mechanical energy.